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摘要
The viscosity of the binary and ternary systems of tragacanth (T), guar (G) and methylcellulose (MC) was obtained by means of a rotational viscometer in the range of concentration from 1 to 10 g/L at 25, 35, 45 and 55C. The modeling was based on polymer concentration, temperature and shear rate. The viscometric parameters, flow and consistency indices were evaluated as a function of the cited variables, obtaining the corresponding correlations. Interactions between polymers are hypothesized because of its structure and molecular weight. An interaction parameter Delta eta(ij)was calculated for modeling. As expected, in all the cases, the apparent viscosity decreases with temperature and it was introduced in the proposed models for T-G and G-MC systems. Synergistic effects were found for T-G in all the cases and G-MC when G concentration was higher than MC concentration. These results could suggest that interactions between MC and G molecules are generated.
PRACTICAL APPLICATIONS
Hydrocolloids are additives used as stabilizers with multiple applications on different industries. In food industry, the interest to find new textures and sensorial properties has led to research on new sources, derivatives or mixtures. In the last case, new ingredients, developed from well-characterized and widely used hydrocolloids have been the subject of recent patents. Additionally, rheological measurements are frequently used to process control and, therefore, it is the main reason to employ correlations of flow properties involving process variables in order to predict the rheological behavior.
This work contributes with models from experimental data to predict the combined effect of polymer concentration and temperature on viscosity of aqueous systems of one hydrocolloid and the corresponding blends of tragacanth, guar and methylcellulose. The extracted information is useful in processing as well as the design of new stabilizers in the food industry.
- 出版日期2011-4
